Transmitter/receiver (interior motion sensor), function - GF80.50-P-4104-02A

Model 202 as of 1.6.97, model 208 (except convertible), 210 with IR interior motion sensor) 

The IMS transmitter and receiver is activated by the PSE control module (combined) (A37)  . Activation is accomplished by communication between the PSE module (A37) and IMS transmitter and receiver via a data bus.

Infrared interior motion sensor (IMS) 

Infrared light is radiated along the inside of the windows by the transmitter. The reflected IR light is converted into an electrical signal by the receiver. A logic circuit processes the electrical signal.

Changes in the reflection corresponding to a certain pattern, are recognized as an attempt to break into the vehicle by the logic circuit and signaled to the PSE control module (A37) via the data bus.

Checking the glass breakage sensors (T-model 202/210 only) 

The glass breakage sensors  are connected to an additional input on the transmitter and receiver module. An interruption in the conductor loops in the glass breakage sensors is recognized as glass breakage by the logic circuit and signaled to the PSE control module (A37) via the data bus.